(س) نَكِرَ يَنْكَرُ نَكَرًا وَنُكُوْرًاnakira yankaru nakaran wa-nukūran: (1) not to recognise something, to regard someone as a stranger (2) to find disagreeable. ﴿فَلَمَّا رَآ اَيْدِيَهُمْ لَا تَصِلُ اِلَيْهِ نَكِرَهُمْ وَاَوْجَسَ مِنْهُمْ خِيْفَةً﴾ (Hūd 11:70)
نَكِيْرٌnakīr (on the pattern of فَعِيْلٌfaʿīl, in the sense of a noun, ism dhāt): denial, disapproval; (from God) seizure, punishment. ﴿فَكَيْفَ كَانَ نَكِيْرِ﴾ (Al-Ḥajj 22:44)
نُكْرٌ وَنُكُرٌnukr wa-nukur (adjective): disagreeable, strange and evil. ﴿لَقَدْ جِئْتَ شَيْـًٔا نُّكْرًا﴾ (Al-Kahf 18:74); ﴿يَوْمَ يَدْعُ الدَّاعِ اِلٰى شَيْءٍ نُّكُرٍ﴾ (Al-Qamar 54:6)
اَنْكَرُankaru (elative, ism tafḍīl): worse, more disagreeable. ﴿اِنَّ اَنْكَرَ الْاَصْوَاتِ لَصَوْتُ الْحَمِيْرِ﴾ (Luqmān 31:19)
Form IV (ifʿāl) اَنْكَرَ يُنْكِرُ اِنْكَارًاankara yunkiru inkāran: not to acknowledge acquaintance, to refuse to recognise; مُنْكِرٌmunkir (active participle, ism fāʿil): one who does not recognise, one who denies. ﴿يَعْرِفُوْنَ نِعْمَتَ اللّٰهِ ثُمَّ يُنْكِرُوْنَهَا﴾ (An-Naḥl 16:83); ﴿فَعَرَفَهُمْ وَهُمْ لَهُۥ مُنْكِرُوْنَ﴾ (Yūsuf 12:58)
مُنْكَرٌmunkar (passive participle, ism mafʿūl, also as an adjective): (1) unrecognised, strange (2) disagreeable (3) evil, i.e. a deed that human nature does not recognise. ﴿اِنَّكُمْ قَوْمٌ مُّنْكَرُوْنَ﴾ (Al-Ḥijr 15:62); ﴿وَيَاْمُرُوْنَ بِالْمَعْرُوْفِ وَيَنْهَوْنَ عَنِ الْمُنْكَرِ﴾ (Āl ʿImrān 3:104)
Form II (tafʿīl) نَكَّرَ يُنَكِّرُ تَنْكِيْرًاnakkara yunakkiru tankīran: to make something unrecognisable, to disguise; نَكِّرْnakkir (imperative, amr): disguise! Only once in the Quran: ﴿نَكِّرُوْا لَهَا عَرْشَهَا﴾ (An-Naml 27:41)